1. Field of the Invention
This invention relates to a process of separating a developing agent and/or a color development accelerator such as benzyl alcohol, etc., from a photographic processing solution and, more particularly, it relates to a process of selectively separating the aforesaid specific processing component or components from a photographic processing solution containing one or both of these materials by bringing the processing solution into contact with a copolymer selected from the group consisting of a styrene-divinylbenzene copolymer and a methacrylic acid monoester-methacrylic acid polyester copolymer.
2. Description of the Prior Art
In the formation of photographic images using silver halide photographic materials, various processing solutions such as developer solutions, stop solutions, fix solutions, bleach solutions (or blix solutions in place of fix solutions and bleach solutions), hardening solutions, neutralization solutions, alkali pre-treatment bath solutions, stabilization solutions, etc., are used.
One particular photographic processing solution contains a developing agent and other various compounds and sometimes after dissolving a part or all of these processing components in water for preparing the photographic processing solution, a specific component or specific components must be removed or separated from the processing solution. Examples of photographic processing solutions from which a specific processing component or components must be removed or recovered are spent photographic processing solutions, a part or all of the photographic processing solutions which became useless after their preparation, or photographic processing solutions which partially overflow from developer baths at the time of supplying the processing solutions thereto as development progresses.
Moreover, since photographic processing solutions generally contain organic compounds having a high biological oxygen demand (hereinafter, referred to as BOD) or a high chemical oxygen demand (hereinafter, referred to as COD), the direct discharge of these photographic processing solutions into sewers or rivers greatly tends to cause environmental pollution or contamination.
Accordingly, in discharging such photographic processing solutions, the materials which tend to cause environmental pollution must be removed, the photographic processing solutions must be rendered harmless, remaining effective processing components must be recovered from the photographic processing solutions, or two or more such treatments in combination must be applied to the processing solutions before discharging. Developing agents and color development accelerators such as benzyl alcohol, etc., contained in photographic developers have a particularly high BOD and COD and, hence, if these components are previously removed or separated from a developer solution when such is to be discharged, the developer solution can be easily treated for waste disposal. Furthermore, since the developing agents, etc., contained in developer solutions are generally expensive, it is undesirable to simply decompose these components in waste treatment and it is desirable from an economical viewpoint to recover these processing components in some manner for reuse.
Various processes have hitherto been proposed for separating or recovering specific components from photographic processing solutions. For instance, a process in which a developing agent, benzyl alcohol, etc., is recovered from a developer solution by adding thereto a salt such as sodium sulfate, etc., to cause salting-out as described in the specification of Japanese Patent Publication No. 33698/73; a process in which these components are extracted using an organic solvent as described in the specification of U.S. Patent No. 2,358,053; and a process in which a dissociated developing agent, etc., is recovered using an ion-exchange resin as described in the specification of U.S. Pat. No. 3,253,920, have been proposed. Furthermore, a proces has also been proposed in which these specific processing components are separated or removed from photographic processing solutions by bringing the processing solutions into contact with activated carbon.
However, these conventional processes as described above are all insufficient from an economical viewpoint. That is, in the above-described salting-out process, a large amount of salt is required to perform the process, which results in increasing the operational cost and further since sparingly soluble compounds are all deposited in the proposed process, complicated steps are required or recovery of each component in a pure form from the solution of a mixture of the salts of these components is difficult. Furthermore, since it is not easy to adjust the pH of the processing solution prior to the addition of a salt for performing the salting-out process, it is very difficult or unsuitable to employ such a salting-out process in laboratories having poor facilities or equipment. In the organic solvent extraction process, a large amount of solvent is used, which increases the operational cost for the process, and further an additional means is required for preventing the occurrence of fire and for maintaining safety and hygiene, which results in increasing the installation cost. Furthermore, since the organic solvent for extraction is dissolved in a photographic processing solution during the operation of the process, it becomes difficult to maintain the values of BOD and COD in the processing solution at a definite level. The ion-exchange resin process as proposed above is very low in efficiency when the compounds to be recovered are not in dissociated states. Consequently, it is very difficult to remove or recover color developing agents such as p-phenylenediamines and 3-pyrazolones using such an ion-exchange resin process. Also, it is impossible to recover color development accelerators such as benzyl alcohol, etc., which are nondissociatable compounds, with the ion-exchange resin process. The adsorption removal process with activated carbon may be excellent in workability and separation efficiency of organic compounds from an aqueous processing solution but almost all organic materials are strongly adsorbed on activated carbon employed at the practice of this process. Thus, complicated and high cost techniques are involved to recover the adsorbed materials by elution. Also, it is difficult or troublesome to regenerate the activated carbon once used and, in addition, the cost required for regenerating the activated carbon is high. Furthermore, it is also difficult to dispose of the activated carbon once used. Moreover, activated carbon is subdivided into powders at use due to its comparatively low mechanical strength and thus it is scattered off or enters into the processing solution as a powder. Therefore, in using activated carbon, a complicated procedure is required for preventing the occurrence of the above-described difficulties.